Electro-hydraulic drilling is known. By way of non-limiting example, electro-hydraulic drilling may be implemented while drilling productions wells used to extract gas, oil, water, and/or other materials from the Earth. In existing approaches, an electrical spark is typically created between electrodes at a drill head. A pulse of electricity at high peak power is then passed through the spark. This forms a rapidly expanding plasma that creates a shock wave. These shock waves can be so powerful they can crush rock. Such a shock wave can be controlled to crush the rock within a rock body just ahead of the drill head to less than one millimeter in size. Typically, shock waves are repeated ten to fifty times per second to drill into the rock body.
A fluid (e.g., water, mud, and/or other fluid) is often used to remove rock debris above the rock body. The fluid surrounds the drill head and flushes out rock particles. In existing approaches to electro-hydraulic drilling, a significant number of electrical sparks form only or primarily in the fluid, rather than extending into the rock body. Shock waves that emanate from electrical sparks within the rock body are tension waves. When the electrical spark forms only within the fluid, resulting shock waves are compression waves. Tension waves are more efficient at breaking up the rock body, relative to compression waves.